Reducing zinciferous material



ugf, 8, 31.933. E. c. HANDWERK E T AL.

REDUCING ZINCIFEROUS MATERIAL Filed June l5, 1952 2 SheetS-Shee'i; l

l NVENTOR ,EQ-um C IQMMMQ @m/Q ATTORNEY Aug., ww

E. C. HANDWERK El' AL REDUG ING Z INCIFEROUS MATERIAL Filed June l5,1932 2 shets-sheet 2 I I I I INVENTORS EMM C. Hm Ggl 777mm ATTORNEY5Patented Aug. 8, 1933 UNITED STATES PATENT OFFICE REDUCING ZINCIFEROUSMATERIAL Application June 15, 1932. Serial No. 617,294

12 Claims.

This invention relates to the reduction of zinciferous material withcondensation of the resulting zinc vapor, and has for its object theprovision of certain improvements in the utilization of the exhaustcondenser gas for generating heat.

The vapors evolved from the chamber or retort in which oxidic zinc oresor the like are reduced by carbonaceous reducing materials contain anamount of carbon monoxide gas at least equal in volume to the zinc vaporpresent and generally in substantial excess of this amount. The carbonmonoxide gas that accompanies the zinc vapor is usually permitted toescape from the zinc condenser after the condensation of the zinc vapor,generally carrying with it a substantial amount of zinc in the form ofzincv vapor, zinc dust and/or zinc oxide. It has heretofore been thegeneral practice to ignite this carbon monoxide gas at the condenseroutlet and burn it Without utilizing its fuel value.

The aim of the present invention is to provide an improved method of andapparatus for utilizing the fuel value of the exhaust condenser gas andfor recovering the zinc values contained therein. The inventioncontemplates more particularly the treatment and utilization of theexhaust gas from condensers attached to continuously operated verticalreducing chambers delivering a constant ow of gas rich in zinc vapor andcarbon monoxide.

An apparatus for therecovery of the fuel and zinc values of condenserexhaust gas must fulfill the following requirements:

(1) vThe operation of the reducing chamber and the zinc condenser mustnot be interfered with by alteration of the gas pressure therein, and inparticular the escape of the exhaust gas from the condenser must not behindered.

(2) Air must not enter the apparatus because of the danger of explosion.

3) The gas must be'cooled as a further precaution against explosion andin order to remove Water vapor that the gas may have taken up from waterused for washing or cooling purposes and in Water seals.

(4) Zinc dust and zinc oxide must be re.`

moved from the gas and collected in such form that they may be readilyremoved. y

f 5) The apparatus must be hermetically sealed so as to prevent theentrance of air or the escape of carbon monoxide gas.

(6) The cleaned gas must be delivered to the fuel gas pipe line at a xedand uniform pressure. (7) The apparatus must be easy to supervise (Cl.'Z5-28) and operate, and in particular periodical dismantling andreassembling of vthe apparatus must not be necessary in connection withthe operations of charging and discharging the reducing chamber, tappingthe condenser or cleaning out the condenser. i

The method of this invention carried out inthe apparatus of theinvention admirably meets all of these requirements. In accordance withthe invention, the exhaust condenser gas is Withdrawn from the condenserand passed through a hermetically closed system `(inhibiting `theentrance of air and the escape of carbon monoxide) to an appropriatecombustion means for utilizing the gas in generating heat. The inventionis particularly characterized by promoting the passage of the gasthrough the closed system by an aspirator, preferably a wateraspiratorwhich denser is regulated and controlled to maintain acontemplated and predetermined gas pressure in the condenser therebyinsuring the proper and contemplated operation of both condenser andreducing chamber.

The accompanying drawings illustrate, somewhat diagrammatically, anarrangement of apparatusembodying the principles of the invention. It isto be understood that the details of construction, and arrangement shownin the drawings 'are illustrative and not restrictive of the invention,and thoseskilled in the art will recognize that the arrangement ofapparatus illustrated in the drawings is susceptible of variousmodifications Without departing from .the spirit of the invention. Inthe drawings Fig. 1 is an elevation of the apparatus,

Fig. 2 is an elevation at right angles to that of Fig. 1, p

Fig. 3 is an enlarged detailed elevation of that part of the apparatusfor treating the exhaust condenser gas, and Y Fig. 4 is a similarlyenlarged and detailed elevation at right angles toV that of Fig. 3.

Referring to the drawings, the reducing chamber is shown as a verticallydisposed and externallyheated retort 10 of rectangular cross section.The retort is mounted in an appropriate furnace structure havingcombustion chambers 11 along each of the wide sides of the retort.Producer or equivalent fuel gas is delivered to the top of thecombustion chambers through ports 12 in a manifold 13 connected by a ue14 with the fuel gas' main 15. Air preheated in a recuperator 16 isdelivered to the top of the combustion chambers, along with the fuelgas, in conventional manner.

The upper end of the retort 10 preferably extends a substantial distanceabove the upper end of the furnace structure and constitutes aprulongation 17 in which purification of the zinc vapor may be carriedout as described in United States Patent No. 1,749,127, March 4, 1939.During operation, the vertical retort 10 and its prolongation 17 arekept full of thecharge of nondistintegrating agglomerates of zinciferousmaterial and carbonaceous material, fresh agglomerates being introducedthrough the charging well 18 and spent residues being withdrawn from thebottom of. the retort as required. The reducing or smelting of theporous charge of agglomerates of mixed zinciferous and carbonaceousmaterials is thus conducted in a continuous manner with the delivery tothe condensing apparatus of a substantially constant and uniform flow ofgas rich in zinc vapor and carbon monoxide. Thus, the zinc vapor andcarbon monoxide gas evolved from the retort 10 ascendthrough the columnof agglomerates in the prolongation 17 and pass through a down-comer 19into a condenser 20 where the greater part of the zinc vapor iscondensed to molten zinc. Carbon monoxide gas and other permanent gasesthat accompany the zinc vapor ascend through the condenser stack 21 fortreatment in accordance with the principles of the invention.

The equipment for treating the exhaust condenser gas is shown in detailin Figs. 3 and 4 of the drawings. A cylindrical gas scrubbing column ortower 22, open at its bottom, is connected near its lower end with theupper end of the condenser stack 21 by means of a downwardly directedpipe 23. A scraper 24 is disposed within the pipe 23 for cleaning outthe gas connection between the condenser stack and the scrubbing column.The pipe 23 is provided with a slide damper 25 for closing the gasconnection between the condenser and the scrubber when desired ornecessary. The top of the condenser stack 21 is normally closed byacover 26 which may be removed, when the damper-25 is in its closedposition, to permit the escape of the exhaust condenser gases.

Thescrubber 22 may be made of sheet iron or equivalent metal. It isclosed at its top by a water-sealed cap 27 providing a-safety valveoutlet in the event of an explosion within the scrubber. The cover 27 isprovided with a removable cap 28 permitting the escape of gas to theatmosphere in the eventof operating diiculties in the gas circuit, suchas clogging of the aspirator or the like. The open bottom of thescrubber 22 extends an appropriate distance beneath the water level in atank or settling chamber 29.

The tank thus serves both as a water seal for the lower end of thescrubber and as a primary settling chamber for zinc dust and zinc oxide.

A removable spraying nozzle 30 extends through the cover 27 into the topof the scrubber 22 and is connected by a flexible pipe or hose 31 with afresh water supply pipeline 32. The pipe line 32 is equipped with avalve 33 and a pressure gauge 34 to regulate and indicate respectivelythe water pressure.

The top of the scrubber 22 is connected by a pipe 35 (equipped with aclean-out scraper 36) with a water aspirator 37 supplied with waterthrough a flexible pipe or hose 38 connected to a pipe line 39. The pipeline is equipped with a control valve 40 and a pressure gauge 41.

The water aspirator 37 is downwardly directed and serves to withdraw gasby suction from the scrubber and to force it through a pipe 42 into agas chamber or compartment 43 at one end of the settling chamber 29. Thegas compartment is formed by a transverse baille 44 extending from thecover of the tank 29 to well beneath the level of the water therein, andabout midway of the length of the tank. The top of the gas compartment43 is closed by a water-sealed cap 45. A pipe 46 connects the gascompartment or chamber 43 with the combustion means for util- -lizingthe cleaned gas in generating heat.

A water overflow pipe 47 .maintains the contemplated water level in thetank 29 and conveys the overflow water to a secondary settling chamber48. An overflow launder 49 connects the chamber 48 with anothersecondary settling chamber 50. The Ychamber 50 has a water overiiowoutlet 51 leading to waste. The water for the aspirator 37 is suppliedfrom the tank 50 through a pipe 52 and a water pump 53 having itspressure side connected to the pipe line 39.

The exhaust condenser gas flows into the lower end of the scrubber 22through the downwardly directed connection 23, and the gas then ascendsin the scrubber against the downwardly directed Water spray from thenozzle 30. The water aspirator 37 withdraws the gas by a regulated andcontrolled suction from the top of the scrubber 22 and forces the gasinto the chamber 43. The zincdust and zinc oxide in the exhaustcondenser gas are carried down into the settling chamber 29 in part bythe spray in the scrubber 22 and in part by the water jet of theaspirator 37, and thus enter the settling chamber 29 in suspension inthe water. Zinc dust and zinc oxide settling in the primary settlingchamber 29 are periodically scraped out through the inclined end of thechamber, the door 29' in the normally closed top of the chamber beingopened for the purpose. The excess water supplied to the primarysettling chamber 29 by the scrubber A22 and aspirator 37 escapes throughthe overow pipe 47 into the rst secondary settling chamber 48. Theamount of water overilowed to waste from the secondary settling chamber50 through the pipe 51 is equal to the amount of water introduced intothe system by the sprayer 30. The pressure of the water supplied to theaspirator 37 may be regulated by means of the valve 40 and the amount ofwater supplied to the aspirator is adjusted to the amount of gasentering the scrubber. When the gas pressure in the condenser orreducing chamber, as shown for example by an appropriate gauge 54 at thetop of the retort, increases above normal, the valve 40 is opened widerto supply more water to the aspirator thus creating a higher suction andpressure to take care of the increased gas volume. Conversely abnormallylow gas pressures in the condenser or reducing chamber are compensatedby decreasing the suction effect of the aspirator 37.

The water aspirator is of particular advantage in conveying the exhaustcondenser gas through the scrubber and into the fuel gas line, since itobviates the use of mechanisms that might be clogged up and stopped byzinc dust and zinc oxide. In practice, we have found the Water aspiratorgreatly superior in reliability of operation to mechanical pumps andfans.

For the treatment of the exhaust condenser gas from a condensercondensing approximately three tons of zinc per day of twenty-four hoursa scrubber 18 inches in diameter and 3 feet in effective height has beenfound adequate. The spray 30 used with this scrubber has a nozzle 4.5millimeters in diameter and deliver two gallons of water per minute at apressure of 25 pounds per square inch. The aspirator 37 has a four-inchinlet and outlet and contains a six millimeter spray nozzle and uses 6to 8 gallons of water per minute at a pressure of 25 to 35 pounds persquare inch (this water being recirculated clarified water from thesettling chambers). This aspirator delivers gas at a pressure of 0.5 to0.8 inches water column. The volume of condenser gas treated by thisequipment is 25 to 35 cubic feet (or more) per minute at 0 C. andatmospheric pressure. This gas enters the scrubber under its ownpressure at a temperature of about 40G-450 C. The scrubber cools the gasto about -60" C. and removes about 9095% of the zinc dust and zinc oxidein the gas. The aspirator further cools the gas to about 20-30 C. andremoves substantially all of the zinc dust and zinc oxide that remain init after the treatment in the scrubber. The cleaned gas has a heatingvalue of about 250-300 British thermal units per cubic foot.

In the apparatus shown in the accompanying drawings, the clean gas owsthrough the pipe 46 into the fuel gas ue 14 of the reducing furnace. Itis preferable to supply the cleaned exhaust condenser gas to the nue 14rather than directly to the combustion chambers of the furnace, becausethe clean gas (mainly carbon monoxide) is then given an opportunity tothoroughly mix with the fuel gas supplied through the pipe 15, therebyinsuring the delivery to the combustion chambers of a practicallyuniform composition of fuel gas. Where the cleaned exhaust condenser gasand producer gas are supplied separately to the combustion chambers 11,irregularities in temperature will develop on account of the fact thatthe cleaned exhaust condenser gas has a substantially greater thermalvalue than vordinary producer gas.

We claim: Y

1. The improvement in the reduction of zinciferous material andcondensation of the resulting zinc vapor which comprises passing theexhaust gases from the condenser through a closed system to a combustionchamber associated with the reduction retort for utilizing said gases ingenerating heat, promoting the passage of the gases through said systemby aspiration with liquid, and regulating the suction effect of saidaspiration upon the exhaust gas outlet of the condenser to maintain apredetermined gas pressure in the condenser.

2. The improvement in the reduction of zinciferous material andcondensation of the resulting zinc vapor which comprises passing theexhaust gases from the condenser through a closed system to a combustionchamber associated with the reduction retort for utilizing said gases ingenerating heat, washing said gases in the course of their passagethrough said system, and promoting the passage of the gases through saidsystem by aspiration with water.

3. The improvement in the reduction of zinciferous material andcondensation of the resulting zinc vapor which comprises passing theexhaust gases from the condenser through a closed system to a combustionmeans for utilizing said gases in generating heat, washing said gases inthe course of their passage through said system, promoting the passageof the gases through said system by aspiration with liquid, andregulating the 'suction effect of said aspiration upon the exhaust` gasoutlet of the condenser to maintain a predetermined gas pressure in thecondenser.

4. The improvement in the operation of reducing a porous charge ofagglomerates of mixed zinciferous and carbonaceous materials in anexternally heated upright reducing chamber and condensing the resultingzinc vapor which com-A prises passing the exhaust gases from thecondenser through a closed system to a combustionl means for utilizingsaid gases in the heating of said chamber, washing said gases in thecourse of their passage through said system, promoting the passage ofthe gases through said system by` aspiration with water, and regulatingthe suction effect of said aspiration upon the exhaust gas 6. Thecombination with a retort with `im-` perforate walls for reducingzinciferous material and an associated condenser, of an aspirator forpromoting the withdrawal of they exhaust gases from the condenser into aclosed system communicating with a combustion chamber associated withsaid retort for utilizing said gases in generating heat, and meansincluded in said system for cleaning said gases.

. '7. The combination with an externally heated reducing chamber forreducing zinciferous material and an associated condenser, of a Wateraspirator for promoting the withdrawal of the exhaust gases from thecondenser into a closed system communicating with a combustion meansthermally associated with said reducing chamber, and means included insaid system for washing said gases. Y

8. The combination'with a furnace for reducing zinciferous material andan associated condenser, of a gas washing column communicating near itslower end with the exhaust gas outlet of the condenser and having nearits upper end a gas outlet, means for spraying water downwardly throughsaid column, a settling chamber beneath said column for collecting theWater sprayed therethrough and adapted to contain an appropriate body ofwater to seal the lower open end of the column, a downwardly directedWater aspirator operatively associated With the gas outlet of saidcolumn for promoting the withdrawal of gas therefrom and the delivery ofthe gas to a compartment at one end of said settling chamber, ,and meanspermitting the flow of gas from said compartment to a combustion meansfor utilizing the gas in generating heat.

9. In the reduction of zinciferous material to produce binc metal, theimprovement which comprises subjecting the exhaust gases from thecondenser to a scrubbing action by aspiration with water, placing thecondenser under controlled suction by regulating said aspiration toobtain optimum condensation of zinc vapor in the condenser.

10. In the reduction of zinciferous material to produce zinc metal, theimprovement which comprises withdrawing the gases from the condenserunder suction by aspiration with Water, and regulating and controllingsaid suction to maintain a contemplated and predetermined gas pressurein the condenser to obtain optimum condensation of zinc vapor therein.

11. In the reduction of zinciferous material to produce zinc metal, theimprovement which comprises subjecting the exhaust gases andaccompanying zinc containing particles to a preliminary scrubbing actionwith water, then subjecting the preliminary Washed gas to a secondscrub' bing action by aspiration with water adapted to place thecondenser under suction, and regulating and controlling said suction tomaintain a contemplated and predetermined gas pressure in the condenserto obtain optimum condensation of zinc vapor therein.

12. In the reduction of zinciferous material to produce zinc metal, theimprovement which comprises continuously withdrawing the gases from thecondenser by aspiration with water, continuously returning the water atleast in part to subject further amount of the gases from the condenserto aspiration, carefully regulating the strength of said aspiration tomaintain a desired and predetermined gas pressure in the condenser toobtain optimum condensation of zinc vapor therein.

ERWIN C. HANDWERK. GEORGE T. MAHLER.

